Alien Exoplanet Season Changes May Be the Hidden Key to Finding Extraterrestrial Life
The search for extraterrestrial life doesn't begin and end with intercepting radio signals from a distant alien civilization—or spotting giant alien constructions with telescopes. NASA has already identified over 3,700 exoplanets and confirmed that over 900 are terrestrial (meaning they're solid and rocky, like Earth), which means that we've got a whole host of planets to search for traces of life. Since we can't visit them all, our best bet is to search for biosignatures—indirect evidence like atmospheric gases that may point to life. Luckily for us, new research may have found an ingenious way to make that search a lot more efficient.
Right now, the search for biosignatures in an alien planet's atmosphere can be boiled down to "Does it have methane?" and "Does it have oxygen?" If a planet has one of those, then there may be life present, but we're not totally sure—methane, for example, can be produced by things other than biological processes, so there's the potential for false positives.
Instead, researchers from University of California, Riverside's Alternative Earths Astrobiology Center have proposed looking for seasonal changes in these key gases to see if there are patterns that show life (like plants) is present. For example, plants growing in the summer (or its alien equivalent) would release less carbon dioxide and more oxygen.
According to the lead author of the research, Stephanie Olson:
"Atmospheric seasonality is a promising biosignature because it is biologically modulated on Earth and is likely to occur on other inhabited worlds," Olson said in the statement. "Inferring life based on seasonality wouldn't require a detailed understanding of alien biochemistry because it arises as a biological response to seasonal changes in the environment, rather than as a consequence of a specific biological activity that might be unique to the Earth."
With the aid of new telescopes, this combination of searching for biosignatures and the distinct patterns created by life might be the fine-toothed comb astronomers and astrobiologists have been looking for.